Wollen Sie mir bitte behilflich sein

Wollen Sie mir bitte behilflich sein?

Ich möchte Sie bitten, mir bitte behilflich zu sein.
Ich finde die Buchstaben R und S sehr schwierig auszusprechen.

Could u tell me whether I pronounce the following words in the right way?

The 's', 'sch', sp' and 'r' are nearly all correct, though the s-sounds are a bit too long for normal speech (you probably did this for emphasis).

Schon: the vowel is flat and not nasalized. The n should be pronounced in the same way as you do in 'schön'.

schön: perfect, like a native speaker.

sie, sehr, sprechen: ok, but a bit unnatural because the initial consonant or consonant-cluster is held too long.

Moritz: it's a long and open 'o', you pronounce it like a short and closed 'o'. This 'o' and the 'o' of 'schon' should be nearly the same in quality, it's just a little bit shorter. The 'r' is a bit too much in the back of the mouth, it sounds too much like 'ch' in 'Buch'. If you want and if that's easier for you, you can use the trilled 'r' instead of the uvular 'r'. Both r-variants are correct, the trilled 'r' is more common in Southern Germany.