Start- Run - type "cmd" (no quotes) then click enter
Then type in the DOS-style window
net use <drive letter>: <source> /persistent:yes
For example:
net use d: \\laser-pc\sharedfolder /persistent:yes
You can also browse the network using network neighborhood, find the share you want to map to then rt-click it and choose "map network drive"
If your user permissions are right you could access the c:\ drive on the main PC like as simple as this:
net use k: \\main-pc\c$ (drive letter chosen is a personal preference)
The persistent switch just makes the OS try to map the share every time you login.
Networking rules apply: same IP scheme, subnet mask, workgroup name. User loged in on laptop has to have permissions on the main-pc to access the files.
PM me if you have trouble.