Need advice on toilet training a 10 month old chihuahua.

[WeAreEternal]

I have adopted a 10 month old chihuahua from a family friend.
Basically they bought the dog at 3 months but have struggled to look after him and have finally given up.
He spent his days locked in a utility room while the old owner worked. She made very little attempt to train him at all and simply let him into the garden occasionally, but mostly just put down puppy training pads and cleaned up the mess when he went to the toilet on the floor.
He is a very nervous dog and if someone shouts or if you go near him without talking in a reassuring tone he cowers and urinates, he also urinates if he gets very excited.

The former owner realised she was not able to care for the dog so asked around for someone to take him in, and he has now come to live with us.

I've never had a dog this old who is not housetrained so I could really use some advice as to how to get him trained.
Also any advice about the nervous urinating would be great.

Tia.