samba for absolute beginners?

[sling-shot]

May be you need to be root for the mount to work. Try running PCManFM as root and repeat the procedure.

[nixer]

I have found that the default file manager for LXDE, pcmanfm, is not as "stable" for mounting network shares. 

I suggest that you install and try nautilus as it is more functional and stable for mounting network shares.  Plus, its list of dependencies are not nearly as long as dolphin.  Dolphin would bring in a lot of KDE dependencies, whereas nautilus with its dependencies would not be nearly as large to download and install.

Plus, nautilus has several add-ons that make it even better so be sure to look these over and get what you need.