Hi... imgur is presently the free site that many of the members are using to share photos. Use the BBCODE ( message boards & forums ). You will be advised if your photos are too large for your avatar or signature as they won't be transferred to your profile.
This forum uses 200 x 700 pixels for the maximum signature. This includes words and photo. It helps to fill up the entire space instead of one long column. If you extend beyond then eventually our Forum Master will be reducing it and advising via PM.