Open Mendeley and login to your personal account.
If you want to keep your folder structure and have exported individual RefWorks folders to RIS files, you'll want to recreate these folders in Mendeley first. Click on on Create Folder and choose a folder name. If you do not wish to import your citations into a folder, select All Documents.
Select File -> Import... -> RIS - Research Information Systems (*.ris)
In the bottom right, use the dropdown to select All supported formats. Click on the file you exported from RefWorks. Click Open.
Your citations are now imported from Refworks and you will see a confirmation of the number of imported references at the bottom of the window. Repeat the process for other folders.
Make sure that you check your references to make sure they were correctly imported.
Open Zotero. From the File menu in the upper left-hand corner, select Import.
The Import box will ask where you want to import from. Select File (BibTeX, RIS, etc.) and Next.
Select the file you exported from RefWorks and click Open
A box with the option "Place imported collections and items into a new collection" will appear. You have two choices:
Leave this option checked if you would like Zotero to place your citations into a new, automatically created folder. (Folders are called "collections" in Zotero)
Or, uncheck this box if you would prefer the citations to be imported into the "Unfilled Items" area of your Zotero library.
If you opted to have Zotero create a new collection for your citations, you may rename it if you wish by right-clicking on the collection in the left sidebar and selecting Rename Collection. The default name of the collection is the same as the name of the file you imported.
Your citations are now imported into Zotero and you can repeat this process for the other folders that you have saved.
Check your references to make sure they imported correctly.