could you please read my post again?
i said i am using the first one for internet and tethering, so the procedure is clear.

i was more expecting an answer like: you can find the mms settings under <insert menu here>.

also the APN seems to be my problem.
its trying to send the mms via the first APN and not the second.

here some logging:

Thu Mar 19 15:15:29 unknown MobileSMS[70] <Warning>: copying entity for string: 01xxxxxxxxx
Thu Mar 19 15:15:29 unknown MobileSMS[70] <Warning>: creating new group with recipients: (
<CKSMSEntity: 0x42119f0>
)
Thu Mar 19 15:15:30 unknown com.apple.SpringBoard[30] <Notice>: told to send sms 15
Thu Mar 19 15:15:30 unknown com.apple.SpringBoard[30] <Notice>: adding piece: type:[image/jpeg] partID:[0] previewPart:[-1] duration:[0]
Thu Mar 19 15:15:30 unknown com.apple.SpringBoard[30] <Notice>: data:[0] [/var/mobile/Library/SMS/Parts/06/15/15-0.jpg] contentLocation:[IMG_6807.jpg]
Thu Mar 19 15:15:30 unknown SpringBoard[30] <Notice>: MMS: adding recipient 01xxxxxxxxx/TYPE=PLMN to mms
Thu Mar 19 15:15:30 unknown SpringBoard[30] <Notice>: MMS: encoding 2 parts
Thu Mar 19 15:15:30 unknown SpringBoard[30] <Notice>: MMS: encoding message:
Thu Mar 19 15:15:30 unknown SpringBoard[30] <Notice>: MMS: -----------------------------
Thu Mar 19 15:15:30 unknown SpringBoard[30] <Notice>: MMS: To: 01xxxxxxxxx/TYPE=PLMN
Thu Mar 19 15:15:30 unknown SpringBoard[30] <Notice>: MMS: Subject: aint this sum shit?
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS:
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS: Part 0 (298 bytes):
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS: Content-Type: application/smil
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS: Content-ID: 0.smil
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS: Part 1 (246927 bytes):
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS: Content-Type: image/jpeg
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS: Content-ID: 1
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS: Content-Location: IMG_6807.jpg
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS: -----------------------------
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS:
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS: queuing mms
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: decoding 247351 byte MMS
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: queuing mms message with id 15
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: context 0 is active
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: context 0 is active
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: sending message to http://mms
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: -----------------------------
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: To: 01xxxxxxxxx/TYPE=PLMN
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: Subject: aint this sum shit?
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: Content-Type: application/vnd.wap.multipart.related;type=application/smil;start=0.smil
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: X-Mms-Message-Type: M-send-req
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: X-Mms-Transaction-ID: 1237472131-0
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: From: <insert address>
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: X-Mms-MMS-Version: MMS 1.2
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS:
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: Part 0 (298 bytes):
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: Content-Type: application/smil
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: Content-ID: 0.smil
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: Part 1 (246927 bytes):
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: Content-Type: image/jpeg
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: Content-ID: 1
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: Content-Location: IMG_6807.jpg
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: -----------------------------
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS:
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: queued mms 15
Thu Mar 19 15:15:31 unknown SpringBoard[30] <Notice>: MMS: successfully queued messageId 15
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: sending request to mmsc
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: User-Agent = cvmms/1.0
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: proxy mms:5080
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: binding to context 0
Thu Mar 19 15:15:31 unknown CommCenter[34] <Notice>: MMS: open completed