ANSWER:
That 1st rakah is invalid because you had dropped a pillar. This means that the 2nd rakah replaces it and becomes your 1st, the 3rd rakah becomes your 2nd and the last 4th rakah becomes your 3rd
Now, you need to stand and pray your actual 4th rakah and after you finish tashahud and salutation upon the prophet salla Allahu alaihi wa sallam, and then offer salam and after that you offer 2 prostrations of forgetfulness and then another salam