Very new to Linux so here is what i'm trying to do. i'm trying to connect 3 computers to have them work as one for more memory and more
It doesn't work like that.
Memory has bandwidth measured in tens of gigabytes per second, and latency measured in nanoseconds.
Network bandwidth is measured in milliseconds, and bandwidth in hundreds of megabytes per second, or single digit gigabytes per second for 10GbE.
This means that transferring data between nodes will be very expensive in terms of time and bandwidth, compared to a local memory operation. For some tasks, this is not a big issue. For instance film rendering is trivial to parallelize - simply send a chunk of the file to each node.
Same goes for some other operations, such as compilation, and a lot of heavy calculation; there is very little need for communication between nodes doing different subtasks.
But this does not expand to general computing, in the way you assume. If you want to use a cluster for a specific task, such as compiling or rendering. ask about that. The general use cluster like you seem to expect is simply impractical, and will probably be slower than each of the individual systems.