I found a key which begins with a 1 on my old computer (2013) in a text document  and I have been unable to work out the process from here to get to the bitcoin if it exists.

I have downloaded Electrum and in the import Bitcoin Addresses menu typing my key in does not work and this is the info box:


I believe my key must be p2pkh but typing in "p2pkh:InsertMyKeyHere" does not work.
In this format  p2pkh: X -> Y. Is Y an output or are they both inputs?

I have been unable to type anything into the box which "un-greys" the "Next" box.

Any help working out the process from here would be greatly appreciated.

Cheers