In Step 1 for the basic setup of your rally, you have 60 characters to explain the reason for your rally.
If your reason to rally is more than 60 characters long, you will not be able to proceed to Step 2. The text in yellow indicates that you've surpassed character limit. You can edit and shorten any of the text to proceed to the next step.
Check out this blog post for tips on how to make the most of your Rally name. We also recommend you check out other campaigns using Rally.org to get an idea of how they've set up their campaigns.
For step-by-step instructions on how to set up your campaign, visit this section of the Help Center.