I have read the instructions offered in the FAQ's

What FAQs? Please post a link.

when I type in my filter name and then select "+" after the email addy I get error about filter name already exists...

You'll have to use a unique filter name. https://support.mozilla.org/kb/organize-your-messages-using-filters

Thanks for the reply but that doesn't apply here I don't think. I named my filter "block list" I have about 5 junk mails daily which I r-click on the email address and "create filter from" and on the pop up I select "any of the following" and drop down to delete message and then get the error above. I want to use that filter name for all junk messages...

You can only add a filter "block list" once. It has to be a unique name. But you can then add multiple filter rules underneath that filter.

Having said that, the attempt to fight spam with static filter rules is futile. Use the built-in junk mail controls instead. https://support.mozilla.org/kb/thunderbird-and-junk-spam-messages