In signature campaigns, you pretty much put a message advertising something for the person who runs the campaign. Every campaign has its requirements. You can find a list of the campaigns available here:
https://bitcointalk.org/index.php?topic=615953.0Most of them require having a category of member of above, so you also need to post and participate in the forum in order to get that status.
Hope it helps.
Ok thank you for your answer but as a junior member, how to join the Signature Campaigns of WhyFuture and DIMCOIN for example ??
Do I have to visit their sites to register ?? And if I sign up, what will be the next step to succeed my Signature Campaigns ?? I really can not understand the procedure ??
A certain signature campaigns have a specific criterias that you need to meet before to be accepted. Though, it's still depends on the campaign managers if they'll accept you. You need to READ! and UNDERSTAND! the thread:
Standard Procedure is;
1. Apply w/ format like this:
-Username:
-BTC Address:
-Post to apply:
-Starting Post:
-Wear Proper Signature
2. Then wait for the confirmation of the campaign manager.
The procedures are pretty basic, you just need to follow and understand what is written on the Post. A piece of advised, before joining a campaign be sure that you already have any kind of ideas in regards to this industry. Also make your posts constructive (Intelligent, 75+ characters, on point and on topic).