How to place the chart in the middle.

The middle of the chart is placed like this (the stitch with arrow) in the middle of the front/back piece or mid sleeve.

It says in the pattern that you need to continue working the front piece according to the chart. It is important to position the center of the chart in the middle of the front piece, so the pattern is centered and symmetrical

You have 81 sts on the front piece. Which means, st number 41 is in the middle of the front piece and must be worked with the color in the middle of the pattern according to the chart.
The chart has more than 24 sts and the arrow showing the middle stitch, is pointing at the 13th st in the chart.
Start in the middle of the front piece (st 41) First count 13 sts from the middle of the front piece and off to the right, then the entire chart (24 sts) until you have 4 sts left.

Which means, when you start on the right side of the front piece, you first work the last 4 sts of the chart (from the right to the left), then the whole chart (24 sts) from right to left, and then start from the beginning again so you get the 13th st of the chart in st number 41 on the front piece. Continue the rest of the chart on the other side of the arrow and start from the beginning of the chart again, continue until there are no more sts on the front piece.

If you work in the round and have the same pattern on the back piece, continue here in the same way. Start with the same st in the chart as in the front piece, work from the right to the left, just like in the front piece.

If you work back and forth, start from the wrong side on the next row in the chart, with the st over the st you finished with and work according to the chart from left to right.

See a model where this technique is used.