I decided not to do a step by step zipper insertion on the trousers because I've done one already. Two in fact, and either or will do the trick. I plan to do an invisible zip on both my pairs of trousers. And you know how I feel about invisible zips, and if you don't here's the post I did on how to insert one.
If you feel your fabric is a little to thick to handle an invisible zipper, you have the option of doing a regular zip. Handpicked and lapped is my favorite method. Here's my method and there's also this one from Gertie's blog and this one from the Sewaholic.
Metal zippers from JamieDeLongVintage on Etsy
To top this whole thing off, I'm going to let you in on a secret too. The zippers they make these days are sadly, not as durable as vintage zippers made of actual metal. Especially the invisible ones. So if you are in the market for a metal zipper, which you will not find at your local Joann, take your hunt to Ebay and Etsy. And if you score an invisible metal zipper, you are one lucky duck indeed. I've only found one and that in pale pink.
Oh my goodness! It's onto hemming next! Almost there!