You cannot learn astrology on the Internet. Either you find a teacher, or you purchase the volumes of writings that will tell you how to proceed. Both is good.
Most can be found at The Astrology Center of America
Below is a List of books that you will need to have to do the various aspects of astrology:
1. General Traditional Astrology: All the books by Ivy Goldstein Jacobson
Amazingly, a good starter book is ASTROLOGY FOR DUMMIES by Rae Orion. And at the other end of the scale, for psycho-analytic astrology: SYNTHESIS AND COUNSELING IN ASTROLOGY: The Professional Manual by Noel Tyl.
But for a serious knowedge of basic astrology, you really need the Ivy Goldstein-Jacobson set:
All Over the Earth Astrologically
2. Horary Astrology: SIMPLIFIED HORARY ASTROLOGY by Ivy Goldstein Jacobson
3. Relationship: ASTROLOGY OF INTIMACY, SEXUALITY, AND RELATIONSHIP by Noel Tyl, RELATIONSHIP ANALYSIS by Robert P. Blaschke, and THE ASTROLOGY OF HUMAN RELATIONSHIPS by Frances Sakonian and Louis Acker. Except for Noel Tyl, all of these authors have died.
4. Vocational Analysis: VOCATIONAL SELECTION AND COUNSELING VOLUMES 1 & 2 by Doris Chase Doane; PLANETS IN WORK by Jamie Binder,
5. Prediction: There are so many good ones:
Combined Techniques: PREDICTING EVENTS WITH ASTROLOGY by Celeste Teal,
IDENTIFYING PLANETARY TRIGGERS by Celeste Teal
Solar and Lunar Returns: LUNATIONS AND PREDICTIONS by Sophia Mason, PLANETS
IN SOLAR RETURNS by Mary Fortier Shea, SOLAR & LUNAR RETURNS by Donald A.
Bradley, THE LUNATION CYCLE by Dane Rudyhar, THE LUNAR CYCLE by Francesca
Solar Arc Directions: SOLAR ARCS BY Noel Tyl
Progressions: SECONDARY PROGRESSIONS by Nancy Hastings, PROGRESSIONS IN
ACTION by Doris Chase Doan, PROGRESSIONS by Robert P. Blaschke(especially for
Minor and Tertiary Progressions, DELINEATION OF PROGRESSIONS by Sophia Mason
Transits: HOLOGRAPHIC TRANSITS by Robert Blaschke, TRANSITS: Forecasting Using
the 45 Degree Graphic Ephemeris by Reinhold Ebertin, THE PRACTICE OF
PREDICTION by Nancy Hastings, TRANSITS by Betty Lunstead,
Midpoint pictures: COSI(Combination of Stellar Influences) by Reinhold Ebertin,
PLANETARY CONTAINMENTS by Sandbach & Ballard,
Harmonics: PREDICTIVFE TECHNIQUES IN ANNUAL HARMONICS by Charles & Lois
Diurnal Charts: THE ART OF FORECASTING USING DIURNAL CHARTS by Sophia
Eclipses: ECLIPSES by Celeste Teal
6. Asteroids: The best on asteroids is Martha lang Wescott. I recommend MECHANICS OF THE FUTURE, THE ORDERS OF LIGHT, ARCHITECTS OF TIME, AND the giant cookbook volume of asteroids, ANGLES AND PREDICTIONS
7. Houses: THE ASTROLOGICAL HOUSES by Dane Rudyhar
8. Rulerships: THE RULERSHIP BOOK by Rex E. Bills
9. Want to become an astrologer? VEry hard to make any money at it, but if you are serious, there is a manual to tell you how: ASTROLOGY: A LANGUAGE OF LIFE(vol. 3): A Handbook for the Self Employed Astrologer by Robert P. Blaschke.
10. Sun-Moon Blends: SUN SIGN-MOON SIGN by Charles and Suzi Harvey
11. Health Issues: ASTROLOGICAL TIMING OF CRITICAL ILLNESS by Noel Tyl
12. Harmonic Astrology: HARMONIC CHART by David Hamblin. This is way out of print so you will have to search eBay or Amazon to find a used copy. I got mine from World Books in the UK.
13. Vocational Astrology: IN THE BEGINNING ASTROLOGY and OUTER SPACE TO PLANET EARTH by Ivy Goldstein-Jacobson; VOCATIONAL SELECTION AND COUNSELING, vol 1 and vol 2 by Doris Chase Doane; PLANETS IN WORK by Jamie Binder; THE MIDHEAVEN EXTENSION PROCESS by Noel Tyl. The best of the group is PLANETS IN WORK, but its long out of print.