To be specific on selling, go to manor guy, click him and select "Tally up Indigenous Product." This brings up a list of all the crops you have in your inventory (not Warehouse.)
Double click the crop you wish to sell, and it brings up another screen listing all the manors buying that crop and a 'reward type' of 1 or 2 for each. Look at the top of the box to see what '1' and '2' will give you. For red coda, you wanted varnish, which is '1' reward type. Look to the town buying '1' for the highest price. Select it in the box near the bottom of the screen. (Clicking 'max price' will chose the town buying for the highest price, but it may be a '2' town. It also sets the quantity to all you have.)
To prevent waste, you should manually enter the quantity. To do this you need to know the 'base price' of the mat you are getting. You can look that up here. (
http://lineage2.stratics.com/content/library/items/etcitems.php?type=material) Varnish has a base price of 200a, so you want to turn in a quantity of crops that when multiplied by the manor buying price is a multiple of 200a.
If the manor is paying 300a for each red coda, you need to turn in an even number to prevent waste; 2, 4, 6, etc. On varnish, the loss is small, but if you are getting enria, you can loose a lot (12,000a base price, so at 300a each you need to turn in 40 before getting any; turn in less, you get nothing.)
Once you set the quantity, click the 'okay' (or similar) box at the bottom. It closes this window, but enters you data in the original screen. (on the line of your crop, entries will be seen in the town and quantity fields.) This crop is now ready to sell by clicking the 'sale' box at the bottom, but don't do it yet. (repeat for any other crop you wish to sell.)
When they are all ready, click 'sale.' If the manor is buying, the sale will occur. If the manor is sold out, you must come back and sell at 8:06 pm CST. You can set the sell screen anytime between 8:00 and 8:06, but don't click 'sale' until 8:06. If you are too early, you get a 'manor is undergoing maintenance' message. If you are too late, and others have sold before you, you get a 'failed to turn in 200 red coda' message. Try again the next day.