You don't really need to understand the schematic to build it. The two types of ICs that are used are the 74AC240 and the 74ALS05. (The schematic lists a 54ALS05A, but that is packaged in a harder to use format.) You can search the Internet for those two part numbers and find the datasheets and vendors that carry them. The "AC" and "ALS" are specific types in the TTL family. There are other types that can be substituted if those chips are not avaiable. However, it is best to follow the original design if possible.
Basically, you get some perf board, some DIP sockets, the resistors, capacitors and ICs and solder it all together using short pieces of wire. If electronic assembly is new to you, then perhaps a local tech school or junior college could help. Call the instructors, if you pay for the parts, they may make building this for you an extra credit project for one or more of their students. If the tech school idea does not work out, inquire at your local TV or electronics repair store. They probably know who to local electronic hobbyists are and can direct you to a local person that can help you build it.