how do I enter this expenses?
It's not an expense "per-se". It's a capital improvement that adds to the cost basis of the property. You'll enter it in the assets/depreciation section. Depending on where you're at in the program and what you've already selected, that section might be called "Sale of Assets/Depreciation" now.
You'll enter the asset, cost and other stuff. It gets classified as residential rental real estate. Give it an in service date that is the date of your closing if the work was completed after the last renter had moved out. Where it asks for COST and COST OF LAND, your COST will be what you paid for the improvements, and your COST OF LAND will be ZERO.
Then you'll work through all of your assets again to report the sale of each asset with a portion of your sales price allocated to each asset. Remember, if you sold at a gain, then you must show a gain on all assets listed. Otherwise, depreciation recapture will be wrong and you risk paying more tax on your gain than you should.
