The link posted by Achalveer assumes you have "MyEclipse", which is a very inexpensive commercial plugin for eclipse (Around $40 US per year). If you're serious about Struts development, this would be a very good investment.
If you decide not to purchase MyEcplipse, you should at least install the free WTP plugin. I'd recommend doing this through "Callisto" which will make sure you get the right version. This plugin enables J2EE web development in Eclipse.
Unfortunately, I can't recommend any good, free Struts plugins for Eclipse. The few that I've tried don't work.