Translation of Oberschenkel

Can you translate: Are you using the firefox browser? Install this tool in your browser window. The ones I suggested the other day are the most useful ones, because we would use it for generic terms which differ from Spanish.
I had never heard the phrase before. In America, there are also different idioms than here in England. It seems that the Americans say it differently than we do here in the United Kingdom.
If you're still interested in our agreement, I will be glad to continue to correct your letters and essays. Write it in English, if you do not know a particular word and I'll translate it.