Select that part of the address which you want to keep absolute and then
press F4
For example
to get $A1 select A and press F4
to get A$1 select 1 and press F4
tp get $A$4 select A4...
to get $A$1:$B$10 select A1:B10...
Experiment and you will get the hang of it.
Actually F4 cycles through all the combinations... so can keep pressing it
and stop when you get what you want