Position the rounded end of the tyre lever under the bead and lever downwards. Hook the other end round the nearest spoke.
Work right round the tyre in short sections, pulling the tube out when it is free.
Locate the hole by inflating the tube with a small amount of air and dunking into water - looks for bubbles. Remove any thorns, etc. from inside the tyre. Clean and dry the tube, and then apply a film of rubber solution - slightly larger than the patch that you are using.
When almost dry, remove the silver foil from the patch and smooth it into place. Then peel off the cover.
Fill the tube with a small enough amount of air to give it it's shape. Fit the valve into the valve hole, keep the tube straight inside the tyre, then refit the tyre starting from the valve, using only your hands (if you use levers you could pinch the tube and end up starting all over again). Once the tyre is fully on, push the valve up into the tyre, seat the tyre nicely into the rim, then pull the valve back down - this will ensure that the valve is sitting properly inside the tyre. Make sure that the whole tyre is seated evenly on the rest of the rim
Now inflate your tyre to the required pressure (marked on the side of your tyre).