Do not use too much weight, Remember that keeping a proper form is more important than having a lot of weight. The woodchop designed to train your core, the movement should primarily result in your hips and abs, and not require a lot of arms strength.
This exercise is great for core strength, but your form needs to exactly perfect to do it safely.
There a lot to go wrong here: you should keep the back straight as you go down and bend from the hips, as bending the back under load is really dangerous. You should also rotate from the hips and not from the back and keep the core braced and tight as you lift your arms overhead.
So basically, if you're new at training, you will probably do it wrong, there's a lot to learn and perfect here. So if you still want to do this exercise make sure to have a trainer to guide you. Don't think you can do it right just cause you read something on the internet, You don't want to get an herniated disc when you just started training.