I accessed the microfilm at my local Family History Center. You can find the one nearest to you at this page. Questions about Family History Centers are answered here. More information on what to expect during a visit can be found here. It is a common misconception that one must be a LDS church member to utilize the facilities. This is not true. I am not a member and have had all positive experiences.
I located the microfilm of Pope County, Arkansas wills by checking the Family History Library catalog. I clicked the "Place Search" button. Then I put "Pope" in the place box and "Arkansas" in the part of box and hit enter. I was given one link says "Arkansas, Pope," so I clicked that. Numerous results are shown. I chose "Arkansas, Pope - Probate Records."
One of the titles I was shown was Probate court records, 1830-1978. I then clicked the "View Film Notes" button in the top right of the screen. The first film listed is #1034017.
I wrote down the film number and took it to my Family History Center. I filled out a little form and paid a $5.50 rental fee. 2-3 weeks later, the film arrived from Salt Lake City. The film stays at my FHC and I use their readers. My last day with the film is Nov. 20, but I'll probably renew for another session.
So that's how I got the microfilm that held the will of my spinster aunt. Hopefully I answered Marti's question and maybe yours. If not, just let me know and I'll give it another shot.