When doing GJ the method is to make the first row, first column a 1, and then 0's in the rest of the rows in that column. Since there is a 2 in R1 C1, you would take 1/2 R1 to make the two a one. Then you have to make the 6 a 0, so you would go: R2 - 6R1 (to get rid of the 6)
Now your matrix is:
1 2 | 1/2 0
0 -10 | -3 1
or something like that. Now make the -10 a 1 and make the two a 0 after that. Then the right hand side will be your inverse. There is an easier way of finding inverses for a 2x2 matrix using inverses though.