The app will guide you in learning these lichens. A hand lens with 10 to 30x power is a useful aid in identifying lichens, but if you have good vision, you can make pretty good ids without one. Lichens look very beautiful under magnification and you will find it much easier to identify the lichens you see.
Your first step will be to find a suitable area to survey. You can survey any forested
area, but if you want to maximize the number of lichens you are likely to see try to
find a mature, well-lighted, natural stand of trees with plenty of hardwoods (see the
beginners tutorial for more details about how environmental conditions affect lichen
cover and diversity). There should be at least 20 trees on your plot.
Measure out a circular plot of 35 m diameter with a tape measure and mark the N, S, E and W edges with bright flagging a little more than eye-height. The flagging should be visible from plot center, which should also be flagged. You might also consider placing additional flagging half way between the center and edges of the plot.
Now spend 30 minutes to two hours walking around your plot, inspecting as many of the different microhabitats, trees, and shrubs on the plot as you can. Dead, standing trees and recently fallen trees may be included, but not stumps, decaying logs, soil or rocks. Also exclude the first half-meter up from the ground on tree trunks. Try to find as many lichens as you can without climbing the trees. It's fine and desirable to look at recently fallen branches and live branches and twigs as you are walking around.