LAXs terminal are built in a U-shape. At one end of the U you find Terminal 1 (with WN and HP among others), at the other Terminal 8 with UA Shuttle. The fastest way between T 1 and T 8 is to walk on the arrivals level straight across the two parking structures inbetween. It should not take you more than 5 minutes.

All walking from terminal to terminal around the U-shape on the departure level is fairly easy: You walk on a continous wide sidewalk, without any interruptions such as traffic lights, other roadways, cars etc.

Good luck!