hi,
traditionally the only thing that is necessary it to walk the dogs side by side, on the lead, then allow in turn to get in front so to let them sniff the private bits and not let mount until the interest has grown... there will be a lot of small weeing too, let them (and don;t work the dogs tired...) then it's only the case of attempting the mounting...after a couple of failed efforts they will know what to do...the bitch, if she is ready and experienced, will adjust her rear even to a hopeless first timer...
it is highly discouraged to mate two inexperienced dogs or two dogs that have just met, without proper introduction and fore play...it might get nasty (they tend to fight bitterly if the courting is too boisterous, the bitch is not ready or if there is any problem at all)...and can get painfully for them if they pull off from the tie before they are ready...etc etc..
good luck!