When i do the 6x4/2 lift in maximal weights, do i start out with a weight that i can lift four times in the beggining and when i can fully complete 6 x 4 i move up or i start with a weight that i can lift 2 times and try to do 6x2 one week 6x3 the next week 6x4 and the 3rd week. im confused.

Start with a weight that you can do for 6 sets of 2. What percentage of your 1RM you use depends on your neurological efficiency. For most, it won’t be above 87% of 1RM.