"Easy CurveFit" is a very easy tool to fit curve. Only three steps you should do, and you'll get the fitting curve and the needed parameters. The models include linear and nonlinear.
Regressions:

1. Linear Fit, y=a+bx;

2. Quadratic Fit, y=a+bx+cx^2;

3. Compound Fit, y=ab^x;

4. Logatithmic Fit, y=a+b*ln(x);

5. Exponential Fit, y=a*exp(bx);

6. Power Fit, y=a*x^b;

7. Inverse Fit, y=a+b/x;

8. hyperbola Fit, y=ax/(b+x);

9. Geometric Fit, y=ax^(bx);

10. Geometric Fit, y=ax^(b/x);