BEA recommends deploying ears and wars (drop into the applications directory within your domain), and they support a split development directory (that I haven't used), but if you're just looking for a quick way to drop a jsp in, check out the
Web Application Directory Structure section on BEA's documentation site.
create a directory (myapp or DefaultWebApp or whatever) in the applications directory using the described directory structure, basics being to add WEB-INF dir with web.xml in it and drop your jsp in the the new directory.
The wls server should recognize it as a web app. Go to the deployments node in the console to see it has deployed or try "Deploy a new Web Application Module..."
You should be able to acces the jsp using
http://localhost:7001/myapp/myJsp.jsp