How do you donate in order to have cloning ability?

Cloning is done in the Clone Lab building. Tap this and select the Clone option.

On Mondays - Wednesdays you will be able to see a list of any troops that you lost during the previous kill events. You can use the 'Put in' option to add any resources to let you 'clone' (resurrect) a percentage of them. You will need to buy 'gene fragments' with money tough to clone them all. On Thursday you will be able to collect from here the clones troops.

You can also request donations from others and also tap on the Donate tab at the top to see any other alliance members who have requested help and you can donate to them.