At our age it's kind of fun to play with the kids toys some time isn't it? And I'm sure we could all use a brush up on software development skills.
If you want to get started you might want to use a graphical tool that makes it fun both for adults and for kids. I clearly remember 40 years ago when I was first getting started programming I used a tool called "Carol the Robot".
And you spend time writing little programs to move a little dot around on the screen that represented a robot. Well kids expect more visual things these days and there are lots of tools like "Carol the Robot" that you can get for free.
On the iPad there's an app called Hopscotch which is free and allows you to get the basics of programming. There is a program called Blockly. I spent about an hour the other day playing with Blockly and had a great time with it. And I'm sure your kids will too. There are other tools as well but you can start with these two. Hopscotch and Blockly to get the basics of computer programming down.