From what I know, biomart is rather poor for visual presentation, but it is great for extracting data. To get some data from biomart:

1. Go to: http://www.biomart.org/biomart/martview/3f43ed74bc7f06a23a127864d2fbdb32

2. Database: Ensemble Plants, Dataset: select your organism

3. Go to Filters, and paste in "ID list limit" your selected genes. Keep in mind that these ids should fit the type specified above the list (e.g., for arabidopsis you can use TAIR IDs). 

4. You can then select the desired attributes (e.g., genomic features or homology information). The result will be a textual/tabular presentation that you can download.

Extracting visual representation of a genomic location depends on the organism. Which one is of your interest? Can you give a bit more details on the desired synteny analysis?

Thanks  David for the reply and Yes you are right about Biomart.

What other tool would you suggest me? I actually tried syMAP but it seems to be a bit complicated. The main problem I am facing is that how to highlight or show only a particular gene or family of genes on the genomes? Can you help me with syMAP if you hv some experience.

 I do not have experience with syMAP, but it looks very useful. For representation of genomic loci I have used standard genome browsers (e.g., UCSC or Ensembl). Not sure which can help in your specific application.

OK, THANKS