notation

Click on the note you want the slur to start from, now press "S"
if you want it to stretch the slur to other notes hold Shift and tap right arrow however many times are needed.

Slurs can be added by selecting the notes and pressing "S" or using the Lines palette. Since you specifically mention "from one note to another", be sure you don't really mean a tie - totally different thing, even though the symbols look similar. Those are added using "+" or the tie button on the toolbar, and you don't normally need to enter the second note manually - simply pressing the tie button after entering the first note adds the second and ties them.

See the Handbook under "Slur" and "Tie" respectively for more info.