Once you have found the post you wish to link to, you should be able to see the address in the browser window; for instance, it may be //www.curezone.org/forums/owenlearnsbasiccomputing;) (or the relevant numbers and symbols). You can then highlight this address, in full, and hold down Ctrl as you press C, this will copy the exact address. When you wish to link to the address, you simply paste the address by holding down Ctrl and pressing V.
Should this fail to work (I am not too certain about the WebTV you mentioned), then you can simply take a note of the web address of the post you wish to link to, and then type it out in full (remembering to begin http) which will then display a hyperlink which will take the reader to the relevant page.