Help with Petrus

[ShawnCunningham]

As some of you may know I'm trying to Petrus, but i don't understand steps 4 and 5. Can somebody explain it in more detail and maybe give me some algs?

I have been practicing the 2x2x3 block and can do it in about 15s now.

 

[Lofty]

Step 4 I just completing F2L. You are mainly restricted to RU turns since this will preserve edge orientation. Since its 2-gen it can be done quite fast. You can branch out and use other turns to save moves but you have to be really careful not to mess up edges.
Step 5 is something that really isn't done in Fridrich (well of course it is done but as a part of PLL) you permute your corners. So get them in the right spot regardless of their orientation. All the algs on Petrus's site tho in annoying applets as opposed to written out in notation. You mainly use a niklas but will have to use it twice in some cases unless you learn a second alg.