How to use diff?

[Jared Johnson]

Didn't know if this was appropriate to post to list, but maybe someone can help?  I'm not that new to unix but never had to use diff.  What I can gather is it's similar to patch, but what options should I use with dhcp.  I'm trying to go from bpl6-bpl18 before I start asking a lot of stupid questions on the list.  I'm using RHLinux (kernel 2.0.36) is this the best upgrade to go to?