You can go either to these two sections:
1.
https://bitcointalk.org/index.php?board=161.0 - Marketplace for Altcoins
2.
https://bitcointalk.org/index.php?board=52.0 - Marketplace for Bitcoin
If you have already post a application for a campaign, you have to wait till the Campaign Manager notifies you if you are accepted or not. So you have to check from time to time the campaign if the Manager has already accepting participants and there is a spreadsheet usually found in the first page of the campaign listing all accepted participants. If you don't see your name it means that you are not accepted maybe the campaign is already full or the Campaign Manager has rejected you for (1) your post is not good enough for him/her (2) inactivity on your part. So to get higher chance of getting into a campaign, you must improved your post and add comment that will contribute to the discussion of the subject. Goodluck to you and hope that you can join a signature campaign and start earning bitcoin.