How to update a table by comparing an entry in two other tables in Microsoft sql?

Question

I am new to sql manager. I am attempting to write a query that will compare two tables and display the latest entire between the two in another table. Below demonstrates what I am attempting to do in the query. i am not sure the proper was of accomplishing this. Please advise.

Compare T1 and T2 where Column1 is equal in T1, T2,and T3. Check Column3(date and time) in T1 and T2 to see which has the most current record. Where T1 Column1 = T2 Column1

If 
     T1 and T2 'Column3'(date and time) are equal do not update T3.
     skip record on T3

 Else 
 If 
     T1 Column3 has the most recent date and time than T2 Column3
       1. Delete the record from T3 
          Where T1 Column1 = T3 Column1
       2. Select and Add all Columns from T1 to T3
       3. Update T3 Column4 = 'New'
  Where T1 Column1 = T3 Column1
  Else
      T2 Column3 has the most recent date and time than T1 Column3
       1. Update T3 with all Columns from T2
          Where T1 Column1 = T3 Column1
       2. Update T3 Column4 = 'Update'
   Where T2 Column1 = T3 Column1

   
T1 table1                   
 Column1(Number)
,Column2
,Column3(Date and Time)
,Column4
,Column5
,Column6   

T2 table2
 Column1(Number)
,Column2
,Column3(Date and Time)
,Column4
,Column5

T3 table 
 Column1(Number)
,Column2
,Column3(Date and Time)
,Column4(New/Update)
,Column5
,Column6
,column7