there have been multiple threads on terms of a lease, so look that one up ;). As for if someone would like to ride your horse... I see you live in Alberta. As long as the field isn't wet (there's been lots of rain in Canada) and there aren't too many mosquitoes you could probably find someone for next month. I don't see how you're going to convince someone to ride your horse outside in the winter. Also, the leaser would be paying you to ride your horse on a field, probably all alone and without other horses. Now if you find an experienced horse person who is not doing lessons and does not own a horse and likes to ride alone then i'd say you have a leaser... however most of these people either have a horse or may have children who ride at a stable. I would not suggest leasing your horse out to a child, in your situation there is no supervision or lessons, and you never know what can go wrong. You can try to put in an ad, but I don't see the appeal for very many people, unless you happen to get lucky. I would suggest trying this first and then maybe trying a situation where the leaser pays the board, or you split it. Again, the winter thing is what bothers me most. If it's icy (like last winter ) you can't rely on riding outside, and no one wants to ride outside when it's -30. You would solve this by splitting the fee for a stable with an arena. They will probably have supervision and lessons, which opens up the leaser to being younger teens who are good riders as well and parents who ride of those teens as well.
Leasing is a great opportunity and I would say go for it. You might find a person who'll want to lease in your situation, but to me it's not a long-term option. Summer leases next year could work, but then you'll still have to find someone responsible who likes to ride alone. I wish you the best of luck, and hopefully this helps!