You can attach any files you want to your texts, e.g. pictures, sound files, PDF files etc. There are two possibilities for sending a multimedia message:
Send regular MMS
Go to the mysms settings on your phone and enable the option “MMS” (under "Sidebar - Send & Receive - Send attachment as"). In case the size of the file you'd like to send exceeds the maximum size of an MMS, the message is sent as a normal text including a link to the file. Depending on your operator, you can define the maximum MMS size in “Advanced settings”.
Send attachments as regular texts
To send attachments as a link as part of normal texts, activate the option “SMS” (under "Sidebar - Send & Receive - Send attachment as"). If the recipient uses mysms, your files will be displayed directly in the message. If your recipient is not using mysms, she/he will receive your files as a link. After clicking this link, she/he will be shown the full picture/file. These messages with attachment are handled like regular text messages (not as MMS). Therefore, a message with pictures or files costs you the same as a message without attachment.
It’s possible to send four pictures or files per SMS message, 10 MB maximum per attached picture/file.