Edie had one episode of abcessed anal glands. I noticed that she had been licking that area a lot. The next day I saw a big red bump off to one side of her anus (it was only visible when her tail was up). It looked really painful. I knew what it was, and took her to the vet immediately.
The vet lput her under with gas and then he lanced the abcessed gland so it could drain. There was not much drainage, but every day 3 times per day I held warm compresses to the area to help it drain. The vet put her on antibiotics and it healed up nicely. This incident was over 3 years ago, and there has been no recurrence.
I would not try to express anal glands myself. It is my understanding that if the stools are firm then the stools press against the glands on the way out
and some of the fluid is excreted with the stool. If things are working properly, my vet says you don't need to do regular expressing.
Some dogs seem to have recurring problems with the anal glands, and I have heard that they can be removed, but this would be an extreme case.