Is there a place to go to school myself on dies.

I am going to go with a hornady lnl ap.  Which set of dies do I want?  dies  Are there other options or are dies brand specific?  I am going to reload .223 and 5.56.  Whats the different purpose of the 4" vs the 3.7 vs the full length die?

Thank you

go up to the top of the page and read through all the materials.

The LNL is a good press, I have one and am also new. The dies you are looking for will be the hornady FULL LENGTH dies.

http://www.ar15.com/forums/t_6_42/390234_good_honest_opinion_please.html&page=1#i3618456

Run through that link and the message below it, it outlines the costs of various things you may want to add and have on hand. I also list some part numbers so your die you want is the #546228
Just start doing searches on Hornday 546228 and any other part numbers like that and you find places that have them. Get on lots of backorders.
Also if you have an iphone with those apps where you type in like 'gun shop' and it finds the ones nearest to you....
Do what i did..I moved the map to search BFE places where i figured they did TONS of shooting/reloading (north/south dakota, Texas, new mexico, etc....) and i started calling. Found about 1/3 of what I was looking for that way and all at not too bad prices either. Was good knowing they HAD it and I didn't have to wait. But....that took days and lots of time. For every 20 you call you might find 1 item you need. just hit them with a list of both the name of the item and the manufacturers part number.

Thank you very much for the info.  I am only looking for info on dies.  I know that the lnl is a good press.  I have read dozens of threads and have even used one.  I found a lnl on sale and I am going to order it and the shell plate for sure.  I just have to find/research the dies now.  I am piecing together a setup as I find stuff on sale.  I never thought I would find a press for under 400 but I did.  There is just so much info at the top it is taking me a while to get through it.  I will continue on though.

Thank you.

You can use just about any die in any press.  A die is just a piece of metal that is threaded on the outside and has a specific shape on the inside.  They all work pretty much the same.  

That being said, there are small differences in design like the small base, full length, and neck only.  The BEST resource I have found for understanding the differences is the die manufacturers.  I ordered a catalogue from Redding, and there is very good descriptions with cut-away pictures that describe the differences in the dies.

Your press should use the universal thread pitch that most dies have, unlike something like the Dillon Square Deal B that needs specially made dies or the 50 BMG that has it's own dies and press.  For .223 rounds that will be used in an AR15 platform, I recommend something that full length sizes.  I have used the Dillon .223 dies and the Redding National Match .223 dies.  They both work about the same, but the extra support of the case and the micrometer on the seating dies makes the Redding my favorite.  (By the way, I got them with a discount, they are pricey).  

There is lots of info on neck sizing and small base dies, and all of it tells me that those methods are not appropriate for my reloading on my AR15.  I'll let you do the reading to decide that one for yourself.

The other design feature that is important for .223 is the carbide button.  It usually rides on the decapping rod.  I don't know of any die sets that DON'T use carbide buttons, so you should be ok with any.

You also can mix and match brands, if that is what you want.  You can use a RCBS sizing/decapping, Redding Seating, and Lee factory crimp die if you want.  The brand isn't as important as the method and care taken to set each stage.  Once you get into the details, you may want to look at the Redding S-bushing dies.  I have heard great things about them on this site, just haven't needed to try them yet.

Good Luck.