Not sure if I can explain this. If you go online to aboutknittingmachines.com & find the Brother Knitting Technique book (try under Brother manuals) book page number 80 has directions & pictures. (Book page number instead of file page number.)
Lets say your buttonhole uses needles 2, 3 & 4.
After you knit your first 5 rows, you are going to manually knit needles 2, 3 & 4 onto a piece of yarn, (Use separate pieces for each group of needles. I usually use pieces of crochet cotton because it is smooth & cheap.) These 3 stitches stay on the machine, in work.
Knit the next 11 rows as you have been doing. Push needles 1,2, 3, & 4 out just until the stitches are behind the latches.
Look back at the 3 stitches on the crochet cotton, and pick up the first row of main color loops above the crochet cotton, and hang the loops into the needle hooks of stitches 1, 2, 3 & 4. Because of the U shape of the stitches, you have to pick up the extra stitch on the left. Push needles 1,2,3 & 4 back to knit the picked up stitches through the ones behind the latches.
Transfer the stitch from needle 4 to needle 3, and knit it through the stitch on needle 3. Repeat across the four stitches, leaving the stitch on needle number 1.
Look back at the crochet cotton, and pick up the three main color loops below the crochet cotton, and hang on needles #2,3 & 4.
Knit last 5 rows and finish band. Unpick the crochet cotton so the buttonhole opens.
You may want to practice this on a scrap piece of knitting first. If you pick up and bind off everything correctly, nothing should run.