IN LMDE their should be the standard (gnome) wireless-manager already installed. If not can be installed from repos (if a proprietary wifi card, you'll will need to find how to install. No Jockey App in LMDE!).
alot of XFCE user prefer 'WICD' (in repos also) and their are others (search repos with apt/synaptic/(Mints) software manager.
Hint use only one WIFI manager (may conflict with other)