So you're using LW right? Go to your LW menu Tools>Options>Sharing & press the Add button & select the directory of your Media player's library. Press the Apply button. Simple as that!
When you 1st open LW all the files will always start off in a Red colour. Once LW starts to account for each incomplete AND shared file, they will one by one turn to black. Depending on the no. of files you're sharing & the no. of incomplete files this can take up to several minutes. It's good advice to allow LW to settle down before you do anything.
If you are sharing your LW dwnld folder, & you have dwnlded new files in that one session, you will need to go to the LW library & press the Refresh button. So that LW re-counts what fiels are being shared.
By the way, here's some hnts on optimising LW:
A well set-up LW can start to automatically continue its dwnlding after it's settled down perhaps 2 out of 3 times you open LW. Optimising LW & Maximising Uplds & Dwnlds A (1st post only) & also Part B which is even better & last & least are search & dwnld hints. The latter one I've been thinking about re-writing for some time. That's just for playing it safe. eg- I show all speeds & qualities.