that is difficult to say since you do not have any values listed for the resistors in your drawing. What you need to do is to break it down step by step.
Do you you understand how to calculate resistors in series or in parallel? When in series the values add together. When in parallel the values are calculated by product over the sum, if there are only two resistors, or 1/(1/R1 + 1/R2 + 1/R3 + ...)
So in the schematic I attached you can see that R3 and R4 are in parallel (|| symbol is parallel). Then you have R2 in series with R5. This then gives you (R3||R4) || (R2+R5). This finally breaks down to R1+((R3||R4)||(R2+R5))+R6.
Kind of a lot to take in, but as you break down each set, redraw the circuit to simplify it.