Install Latex .sty and .cls files

Here is how to install a $\LaTeX$ physics.sty in Texlive under Ubuntu. You can do this to any other .sty package you like.

1. Downloaded the physics.sty files from the CTAN repo
2. As super user, create a directory in your $\LaTeX$ installation, mine is /usr/share/texmf-texlive/tex/latex
• sudo mkdir /usr/share/texmf-texlive/tex/latex/physics
3. Move the downloaded file to the new location
•  sudo mv physics.sty /usr/share/texmf-texlive/tex/latex/physics
4. Run  mktexlsr for changes to take effect
• sudo mktexlsr 
5.  Now start using it by adding the following to your  $\LaTeX$ file
• \usepackage{physics}
6. See the documentation on the package's web site for macro definitions
7. Happy  $\LaTeX$-ing

How to include files with spaces in their names into your LaTeX document

Here is how to include figures and files into your $\LaTeX$ document if they have spaces and extra dots in their names.

Suppose your file names are filename.new.pdf and new filename.pd

\includegraphics{{filename.new}.pdf}
\includegraphics{{new filename}.pdf}

(Source)

Latex in Blogger

How do you insert equations like the following in Blogger?
\[ \vec{A}(\vec{r})=\frac{\mu_0}{4\pi}\oint_S\frac{\vec{J}(\vec{r'})\times\hat R}{R^2} d\tau'\]

First, you should know $\LaTeX$ typesetting. Second, you need to copy this script into your HTML template file.  

<script type="text/x-mathjax-config">
  MathJax.Hub.Config({tex2jax: {inlineMath: [['$','$'], ['\\(','\\)']],
                       displayMath: [['\\[','\\]'], ['$$','$$']]}});
  blogger.ui().viewType_.prototype.onRenderComplete=function(){MathJax.Hub.Queue(['Typeset',MathJax.Hub])};
</script>
<script type="text/javascript"
  src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML">
</script>

Here is how you do it. 


1. Go to your posts settings and choose Template from the left-hand bar

2. Click on the "Edit HML" button to edit your template

3. Click on the "Proceed button"

4. Scroll to the point right before the "<\head>" tag and paste the above script, then save your changes.

That's it! Now happy $\LaTeX$-ing.


References:
1. How to get beautifully typeset maths on your blog
2. MathJax: LaTeX on Blogger - finally!
3. Blogging Mathematics