Hi Laura
My advice would be to be very careful teaching spanish walk, expecially if it is the first thing you are teaching with the clicker. Not only is the exercise of Spanish Walk very complex to teach with or without the clicker, your horse needs to be fit enough and working correctly through the back to be able to execute it correctly and also it can go very wrong.
For example, I started teaching my horse Spanish Walk with the clicker when I first started out but inadvertantly taught him to aim for my knee which he got very proficiant at doing! This happened despite having spent hours planning each tiny step of how we would progress.
Why not look into training something a little less complicated at first such as touching an object or fetching an object? These are great things to start with because they are relatively simple to teach and potentially less can go wrong wit the training.
Don't forget, if you are new to clicker training, you will be learning along-side your horse. It is not unusual when first starting out for your horse to get ahead of you in his training and therefore a really good plan is essential
Hope this helps
Marie