HI ,,
Refer the following function module & table ,,
FM:
1 WWW_GET_MIME_OBJECT
2 DP_CREATE_URL
Table: W3MIME, W3MIME
and cl_bcs , Add_attachement type as BMP
first update your Content in mime , then refer this function module... or else if you have FTP access in you client place your File there in CL_BCS choose HTM type inside the use Image html tag source as FTP access . this is bit complicated .. you can try the first one . it will work .