In the blocks editor you manage the blocks of the railway:

A block consists of one or more track sensors and is the smallest unit for all train operations, i.e. a route always starts in one block and ends in another.

For best results, every block should be long enough so that it can hold the longest train.

In the top list you enter the data for the blocks, and in the bottom list the sensors for each block.

SharpMrc has a concept of the directions "Left" and "Right" representing the two only possible driving directions on the railway. "Left" and "Right" is always meant in that sense in the program. Of course that does not prevent you from associating other meanings with those terms, and you should make it clear for yourself what "Left" and "Right" should mean for each track section.

The sensors in the bottom list must be in the order from "Left" to "Right", the leftmost sensor being first, and at least one of the "stop" options must be checked for each direction. You can change the order of sensors with the green arrow buttons.