If you want to contribute an algorithm for an existing sequence, put your program inside the corresponding folder. For instance, if you'd like to contribute a C program for near-rep-digit primes, put it inside the C folder. If the language your program is written in doesn't have a folder yet, feel free to create one.
If you want to contribute an algorithm for a sequence that does not exist yet, create a folder with the sequence name, conventional names are preferred (view oeis.org) and follow the above steps.
Once done putting the program into its corresponding folder, don't forget to update the README.md with a short description of your method. Add installation guide in # Usage section if your program has any dependencies. Don't worry about the # Speed section, I'll benchmark the code and update it accordingly.