De-novo assembly questions

Hello,

I am a new user and am trying to use perform an assembly on my paired read Illumina data using Velvet. I have a few questions. First, I am not able to select the sequences I want to assemble. I have uploaded them, put them in my project, and specified the sequence types. However, when I get to the assembly options the select sequences button is not operational. Second, how to I specify paired reads? Last, can I assemble more than one set of paired reads?

Cheers, Ron