finding out the size of the letters - and the type

[sayhello]

hello dear Ofnuts and Pixlabs
many many thanks - thats just awesome.

the question is- i just downloaded - the file - the calibri-font.

note i am no a Linux Notebook - (mx-linux) - and i wonder how (!!) to integrate this file into the gimp?
how to proceed
look forward to hear from you

regards