Dachshunds can be stubborn and strong willed however, they are also intelligent and willing to please. This makes them very trainable especially with positive reinforcement and commitment on your part. Stop worrying about it, learn all you can and have a plan of action. For the sake of your enjoyment and fun with your Dachshund, you should take action NOW.
A few starter tips:
Watch for signs that your Dachshund puppy wants to go potty - he will stop doing whatever he was doing and may start sniffing the ground. Mine even as a small puppy looked at the back door. I did not notice this subtle sign at first - it was more of a glace but once I got it, life got a little easier. He still does that - no scratching at the door, no barking just a quick look at the door.
Whenever he stops anything. Eating, sleeping, and playing take him outside to go potty - as soon as he stops it is time to pee. Go with your puppy - do not just open the back door and expect him to know what to do. He will have a great time sniffing everything and may or may not go potty. He needs to understand that he should only go potty outside. Also make sure he is not digging under the fence - they love to burrow.
Have an area that you want him to use - make sure the grass is not too long for your puppy. My fully-grown Dachshund only has 3-inch legs. You cannot expect your puppy to get potty trained in grass that is over his head. Dachshunds do not usually go in long grass to pee or poop instead choosing loose soil, short grass, or even concrete.