[Steenrod]

@above, orgopete,I apologize for asking so many elementary questions which reflect a lack of understanding of organic chemistry. The course at my school provides little room for reaction mechanisms and instead focusses on synthesis.In absence of adequate knowledge about how things happen, I am never sure or I never know what to do unless I have seen a similar reaction.

I sincerely apologize again as things have come to a point where I do feel humiliated to ask questions without showing any effort.All the same, come December, I shall start with the book by  Francis Carey and study the subject from the scratch.Please show some patience as you have done for a few more days when my exams will be over and I shall have more time to understand things. 

[orgopete]

Let me guess:

Benzene+[itex]AlCl_3+Cl_2[/itex]=chlorbenzene which reacts with [itex]Mg[/itex] to give phenyl magnesium chloride .What next?

Okay so far. Now you need two different two carbon fragments to react with the Grignard to give the products.

[discodermolide]

If you go to the link I posted you will see the following:
"Synthesis
Phenethyl alcohol can be prepared by a variety of procedures, such as by a Grignard reaction between phenylmagnesium bromide and ethylene oxide:

    C6H5MgBr + CH2CH2O → C6H5CH2CH2OMgBr
    C6H5CH2CH2OMgBr + H+ → C6H5CH2CH2OH

However, the Friedel-Crafts reaction between benzene and ethylene oxide may also be employed:

    C6H6 + CH2CH2O (+ AlCl3) → C6H5CH2CH2OH (+AlCl3)

Phenethyl alcohol can also be prepared by biotransformation from L-phenylalanine using immobilized yeast Saccharomyces cerevisiae."

[AWK]

In both reaction a different isomer is formed. But a correct one can be obtained from the Grignard compound with acetaldehyde.

[blackzoid]

So you could start by alkylating with either friedel crafts acylation (reduce) or alkylation. Then Brominate the benzylic carbon with NBS and uv light. Next do an elimination with sodium tert-butoxide to get the double bond. This molecule(styrene) can now be reacted with B2H6, H2O2, and NaOH to give the anti-markovnikov product which is 2-phenylethanol. If you want 1-phenylethanol just use H2O, H+ instead of B2H6, H2O2, and NaOH.

Hope this helps!

[Steenrod]

Thanks for your answers, all of you!