The front end or just a new rail itself?
Also, what kind of AEG will you be installing it on?
If it's a Marui or clone like SRC, there are a few more steps.
If it's a CA or ICS gun, do the following steps:
-remove old handguards
-place upper rail portion on barrel, making sure the small fork-looking piece goes underneath the inner rim of the barrel nut.
-Tighten the hex screw, which will bring the fork to bear upon the barrel nut and keep the RIS solid
-Pull back the delta ring and install the lower rail
On the front of the RIS on top there is a small flat piece that protrudes past the rail. It is similar to a leaf spring. Make sure this goes INSIDE the front handguard cap. This piece keeps tension on the front of the RIS, and helps keep the lower rail from wobbling.